A need exists for a reliable neutron source in various applications, including calibration, detection and radiography. For example, there is at present an on-going worldwide effort to develop a high-intensity neutron source for neutron radiography with respect to material surfaces or bulk objects. Plasma focus machines have been successfully demonstrated as intense neutron sources, where the neutrons are emitted as a result of deuterium-deuterium (D-D) or deuterium-tritium (D-T) thermonuclear fusion types of reaction. Such focus devices produce high neutron yield per shot and provide a well localized point source, which is very important in neutron radiography. In order to make neutron radiography more practical and popular, radiation hazards must be minimized as well as the construction and operation costs of the neutron source. Such source must also be easily movable and reliable. Although plasma focus devices may satisfy some of these conditions, they are still very bulky and unreliable, typical of high-power, short-pulse devices. Several decades ago, very low-dose neutrons from a discharge tube were produced by deuterium ions from discharge plasma striking a target surface of a cathode on which deuterium was absorbed as gas constituents. In recent years, a high-dose neutron source was developed based on a drive-in target principle by making use of an intense ion beam from particle accelerators. Neutron generation by such ion implantation is very reliable but still requires very bulky ion accelerators.
Also in recent years, there has been renewed interest in loading of deuterium atoms in palladium, under ambient-temperature conditions. The technique used for such loading of deuterium was to pass electrical current through an electrode immersed in a deuterated electrolyte. When the atomic ratio D/Pd of deuterium to palladium is considerably higher than unity, a substantial fraction of the bulk palladium is transformed into the PdD.sub.2 crystal, where the nearest-neighbor distance between deuterium atoms is 0.94 angstrom.
It is therefore an important object of the present invention to provide a new high-dose neutron source, which makes use of plasma ion implantation and avoids the hazards and high costs of the aforementioned prior known methods, as well as bulkiness and other disadvantages associated therewith.
An additional object is to increase deuterium density inside a palladium rod by means of the plasma ion implantation technique to achieve a high concentration of the deuterium atoms.